Castor oil lubricating composition



Patented Oct. 26, 1954 UNITED STATES OFFECIE London, England, assignors to C. C. Wakefield & Company Limited, London, England, a British company No Drawing. Application April 17, 1951, Serial No. 221,538

Claims priority, application Great Britain May 12, 1950 10 Claims. (Cl. 252-33.4)

This invention consists in improvements in the treatment of castor oiland related materials particularly to inhibit oxidation'and/ or drying, gumming or hardening of such materials.

It is well known that castor oil, while possessing excellent lubricating properties, possesses the serious disadvantages of being prone to fairly rapid oxidation by atmospheric oxygen, leading to what is known as drying, namely the hardening of the oil to form a solid resinous product or a sticky gum.

The rate of oxidation of fatty oils depends on the types of fatty acids present and particularly on their degree of unsaturation. The principal constituents of castor oil are the glycerides of ricinoleic acid, a hydroxy-substituted unsaturated fatty acid containing one ethylenic linkage. The oxidation which takes place is almost certainly accompanied by a polymerisation process in which the unsaturated molecules take part. The rate of oxidation and gum formation will, of course, depend on the temperature to which the oil is subjected and the presence of oxidation catalysts.

The invention relates not only to castor oil but to related materials such as the esters of ricinoleic acid, e. g., the simple esters of monohydric alcohols and the polyhydric alcohol esters, to lubricants consisting of mixtures of castor oil and mineral oil (comprising a major proportion of castor oil) and to the so-called casterbase greases containing a major proportion of castor oil.

It is one particular object of this invention to provide lubricating compositions suitable for use in internal combustion engines and for the lubrication of bearings, gears, etc. in which castor oil is the major ingredient. It is known to employ castor oil or mixtures of castor oil with minor amounts of mineral oil as lubricants in a variety of applications and especially in the lubrication of motor car and motor cycle engines where high speeds and severe operating conditions obtain. The excellent lubricating properties and high load-carrying capacity of dustrial uses of castor oil.

blends of castor and mineral oil are used extensuch lubricants are well known, but they suiier from the serious disadvantage of gum formation due to oxidation and polymerisation. Furthei more the free acid normally present to some sistance to oxidation and gum-formation under operating conditions and which are also relatively non-corrosive to composite metal bearings.

Other practical uses of this invention will be obvious to those who are familiar with the in- Thus castor oil and sively for the lubrication of automotive and industrial gears. In such instances the question of corrosion does notarise, but resistance to gum formation is of great importance.

It is already known to inhibit the oxidation of fatty oils by the addition of various organic compounds of which the phenols? (especially the polyhydric phenols) and the aromatic amines are examples.

Such compounds, however, sufier from the disadvantage that their efiect is only of comparatively short duration.

We have found that very much more effective resistance to oxidation and gum-formation can be obtained in the case of castor oil by the addition of a mixture of (a) an organic compound of tin or antimony and (b) an aromatic or heterocyclic secondary monoor poly-amine containing at least three cyclic nuclei, at least two of which nuclei are aromatic nuclei attached directly to the nitrogen atom.

This invention in its'broadest aspect therefore consists of a method of treating an oil of the kind described to inhibit oxidation and gumming which method consists in adding to the oil where R1, R3 and R4 are the same or difierent and are aromatic radicals, and R2 is a condensed aromatic nucleus having at least ten carbon atoms. Any or all of these radicals may be further substituted by alkyl, aryl, hydroxyl or amine groups, although the preferred substituents are hydrocarbon radicals only.

Specific examples of amines which may be employed are:

Phenyl-s-naphthylamine Phenyl-a-naphthylamine BB-Dinaphthylamine Xylyl-p-naphthylamine H C H3 G? Di(e-naphthyl) -.ps henylene diamine wlgnm Phenothiazine Thio-phenyl-B-naphthylamine (benzonaphthothiazine) We have found surprisingly that only amines of the type described are. effective for the purpose, of the present invention, such closely related amines as aand p-naphthylamine. and

diphenylamine being virtually without antioxidant effect.

The organic compounds of tin or antimony to be employed in conjunction with the amines already described are. derivatives, of. divalent (stannous) tin or of antimony and may be, the tin or antimony salts or soaps of organic carboxylic acids, organic sulphonic acids, organic dithiophosphoric acids, or the tin or antimony 7 derivatives of phenols, phenol thioethers, or mercaptans. In the present specification and claims all of such compounds including the derivatives of phenols, phenol thioethers and mercaptans are considered to be salts of organic acidic com- 7 pounds capable of salt formation.

Specific examples of appropriate organic compounds of tin are:

Tin laurate Tin oleate Tin naphthenate Tin petroleum sulphonate Tin derivative of p-tertiary amyl phenol thioether Tin derivative of o-stearyl phenol thioether 011E350 0OS-Oo o 0,111 o o Sn Tin salt of ethylene glycol mononaphthenate cresyl dithiophosphate R.COOCHzCHzO S Where R.COOH=naphthenic acid.

It will be understood that the compounds selected must be soluble in the particular oil in the proportion in which they are to be employed.

We have found that whereas the tin compounds do not themselves possess any appreciable antioxidant or gum-inhibiting properties, they cooperate with the aromatic amines of the type described to give inhibition of oxidation over a period of time considerably longer than could be obtained by the use of the amines themselves in comparable proportions. In this respect the petroleum sulphonates of tin and antimony are particularly efiective.

The aromatic amines used in this invention may be employed in amounts ranging from about 0.1 to about 5.0 per cent and preferably between 0.5 and 2.0 per cent depending on the particular material to be inhibited, and the conditions under which it is to be employed While the tin or antimony compounds may be employed in amounts varying between about 0.05 and 2.0 per cent and preferably between 0.1 and 1.0 per cent. In general the best results are obtained when the amount of tin or antimony compound present does not exceed the amount of amine by weight and preferably the amount of amine employed is at least double the amount of tin or antimony compound.

In certain applications, notably the lubrication of internal combustion engines fitted with composite metal (e. g. copper-lead) bearings, the inhibition of the corrosion of said bearings at elevated temperatures becomes of importance.

We have found that whereas the combinations of additives already described possess excellent anti-oxidant properties they are not efiective in retarding bearing corrosion appreciably.

By the addition of a third additive (0), however, not in itself effective to any great extent in reducing such corrision produced by fatty acids and acidic oxidation products of castor oil, we have found surprisingly that a very substantial reduction in corrosion can be effected.

The additives falling within class (6) which may be employed where necessary in conjunction with the additives of classes (a) and (b) comprise the neutral organic phosphite esters of hydroxy-substituted aromatic thioethers and disulphides.

Specific examples of such phosphite esters are di-(3-carbomethoxy-4-hydroxy phenyl) thioether cresyl phosphite, and the phosphite ester of t-butyl cresol thioether. These materials may be employed in amounts ranging from about 0.2 to about 5.0 per cent and preferably from 0.5 to 2.0 percent.

If desired, further additives may be present in the compositions of this invention. Thus it may be desirable in certain instances to add viscosity index improvers, foam inhibitors, detergents, or ferrous metal corrosion inhibitors.-

In particular we have found that certain additional benefits may accrue from the use in conjunction with the three types of additives already described of the reaction products of aldehydes or ketones with basic water-soluble primary or secondary amines.

We have found, for example that the addition of di-morpholinyl phenyl methane to a castor oil-mineral blend containing additives of types (a), (b) and (0) improved both its resistance to oxidation and its anti-corrosive properties. Advantage may accrue from the employment in certain instances of an antioxidant additive effective at high temperatures, along with the additives of the present invention. Such an antioxidant might be, for example, the metal salt of an organic dithiophosphorio acid or the metal derivative of an alkylated phenol thioether.

Lubricating oil compositions typical of those falling Within the scope of the present invention are:

(1) Firsts castor oil +05% phenyl-p-naphthylamine +02% tin petroleum sulphonate (2) acidless castor oil 10% mineral lubricating oil of viscosity 500" Redwood at F.

+ 1.0 phenyl-,B-naphthylamine +02% tin petroleum sulphonate 7 (3) 87.5% firsts castor oil v 12.5% mineral lubricating oil of viscosity- 44 Redwood at 140 F.

+ 1.0% phenyi-B-naphthylamine- 0.2% tin petroleum sulphonate 2.0% d1 (B-carbomethoxy 4 -v bydroxyphenyl) thioether cresyl phosphite 0.2% dimorpholinyl phenyl' methane By "tin petroleum sulphonate is meant the-Ctin salt of the oil-soluble petroleum sulphonic acids commonly known as mahogany acids.

The following series of tests were carried out to determine the effectiveness of the compounds of the present invention:

A. GUMMINGTESTS AT120 C.

One drop of the oil was placed in the centre of a watch-glass and heated at 120 C. in an oven for a prolonged period. At intervals the watch glasses were withdrawn, allowed to cool and the liquid examined for signs of tackiness or gum formation.

The majority of the test results quoted were the mean of two or more such tests.

Table 1.-Tests in this table serve to illustrate the surprising advantage of the use of the combination of two additives of the present invention over that of either additive used separately.

A blend of 90% acidless castor oil 10% mineral lubricating oil of viscosity 500" Redwood at 140 F. (011A) was used as a basis for experimentation.

cited in Table 1. The same blend was used as before.

45 Table 3 Table 1 Tin Approximate time petro- (hours) to- Test eum min 1 h Approximate 50 8 ngte Gum Additives timethours) present, f of formapercent me 655 tion -Dina htir lamina 0.2 200 Tin orantimony B6 p y Amine compound g g:- 55 2..... Xyglyl-d-naphthylamine 0.2 160 ness 3...-. Phenothiazine (0.5%) 0.2 220.

4".-. genlzlonarljllaathoitiiaziueigg "32.6-.." '225 5.-..-. ip eny enz iue sa ver None None 18 rated solution, less than 2.... .do. Tinh peitrrzllelzi ym) sul- 18' 23 0.5%).

p onae D hth 1-' n n 1- 0.2 320 345 Phenyl-fl-naph- None. -1 no 125' lnfi gt ioz y y (1%)- l fl-Naphthylimine (0.5%)... 02 Less than 60. 85 4-..- r -fi- 80 90 Diphenylamine(0.5%) 0.2 40 s5 E Triphenylamine 0.2 is 28 5-... Phenyl fl-naphrm petroleum sui- 320' no thylamine (1%). phonate (0.2%). 6..-. Phenyl-fl-naph- Tin petroleum sui- 157 190 I 20115; i a m in e phonate (0.2%). 65

. a 7 Phenyl-B-naph- Tin petroleum 5111- 156 200 t h Y1 amin e phmte (111%), The last three results are quoted for cornpara P 1.0% h A n t 1 160 180 tive purposes to illustrate the relative 1neiiect1ve 5 5 -5 1 31 g g ggg ggw ness of certain amines closely related to those of 9 P 5921- n h N n 115 T35 7 the present invention.

i g 'g fi 8 Table 4.-Tests in this table illustrate the range m l %1- M h Tm etmleum ml 160 p 185 of ricinoleic acid derivatives which may be in- 61515111319 pho1Pate(0.2%).. hibited against gum formation by the additives .0% of the present invention, and also the use of supplementary additives.

Table 2.-Iests in this table illustrate the range of tin and antimony compounds which may be employed in conjunction with a typical amine.

A blend of acidless castor oil and 10% mineral lubricating oil of viscosity 500" Redwood at 140 F.-Oil A) +phenyl-fl-naphthylamine (PBN) was employed throughout.

Table 2 Approximate time (hours) es 0 present Metal compound added 111% percent dence Gum of formataekition ness 1- 1.0 None 2.... 1. 0 Tin petroleum sulphonate (0.2%) 320 440 3"..- 1. 0 Tin naphthenate (0.2%) 170 185 4. 1. 0 Tin oleate (0.2%) 125 5.... l. 0 Tin derivative of p-tertiary amyl 165 180 phenol thioether (0.2%). 6....- 0. 5 None 80 90 7.... 0. 5 lin petroleum sulphonate (0.2%) 157 190 8..... 0. 5 Tin laurate (0.2%) 120 130 9 0.5 Tin derivative of o-stearyl 130 phenol thioetlier (0.2%). 10.... 0. 5 Tin salt of ethylene glycol 115 125 mononaphthenate crcsyl dithiophosphate (0.2%). 11.... 0.5 Antimony petroleum sulpho- 160 nate (0.2%). 12..-. 0. 5 Antimony naphthenate ((12%).. 120 135 While, therefore, benefit accrued from the use of a wide variety of tin and antimony compounds, the petroleum sulphonates were outstandingly effective.

Table 3.-Tests in this table illustrate the types of amines which may be employed in carrying out the present invention, in addition to those already Table 4 Approximate time (hours) to- ?g Material inhibited Inhibitors added Incidence Gum of tackiformancss tion 1 Firsts castor oil None 21 28 l PhenyhS-naphthylamine. 2 do 0.2% Tin petroleum sulphonate [2.0% Di(S-carbomethoxy-ihydroxy-phenyl)thioether cresyl phosph 400 440 907 m t l 0.2% Dimorpholinyl phenyl methane aci ess cas or or V {107; mineral 011A 1 h'""]';9"511"': 18

p cny -nap y amme 4 $3.? 552? 8%? {0.2 tin petroleum sulphonate 230 250 1 2% di(3-carbornethoxy4-hydroxyphenyl) cresyl phosphite {5 8% g gjff 22 3 IAS No. 4 with the addition of 0.2% dimorpholinyl phenyl methane 250 275 6 Butyl rlcinoleate None 7 do 1% phenyl-B-naphthy1amine g vzjl .do. 1. (i..i i -4 its No.7with the addition of0.27

ycer ir cino eate one 10 do y {1% pheny1-a-naphthylamlne 0.2% tin petroleum sulphonate B. CORROSION TESTS The following test was employed for obtaining information as to the tendency for corrosion of composite metal bearings, particularly copperlead bearings, to occur in use of lubricating compositions provided by the present invention.

400 ml. of lubricant was weighed into 1500 ml. tall lipless glass beakers, eight of which were heated in a circular electrically heated oil bath thermostatically controlled to maintain the lubricant temperature at 140 C. The beakers were equipped with closely fitted aluminium covers having central slides which were normally closed but capable of being opened for the insertion of a test specimen. The slides when closed allowed sufiicient clearance for centrally placed steel stirring rods to revolve freely. The latter were electrically driven from a common driving shaft at 4001-40 R. P. M. and carried at their lower end Tests were conducted for 12 hours in two periods of six hours, the copper and lead specimens being removed every two hours and replaced by fresh clean ones. Copper catalysts were cleaned with carborundum powder and washed in petroleum ether. Lead specimens were flattened, scraped with a special scraper and finally polished by brushing in one direction with file carding before washing in benzene and weighing. After a 2 hour period a further washing in benzene, brushing with a camel hair brush and reweighing was effected. The total corrosion was calculated by adding together the weight losses of the lead specimens after each two-hour period.

The following test results illustrate the effectiveness of the hydroxyaryl thioether phosphites in conjunction with the other additives of the present invention, in inhibiting corrosion of lead at elevated temperatures.

Table 5 Test Additives Lead specimen weight loss umulative) after 6 12 hours hours 2 4 hours hours {90% acldless castor oil..-

10% mineral oil A {90% acidless castor oil 10% mineral oil A oil..-

{90% acidless castor 10% mineral oil A. phosph1te {90% acidless castor oil.

10%mlneral0ilA 2 10% mineral oil A v 5 {90% acidless castor oil phcsphite.

}None }0.5% phenyl-fl-naphthylamlne v 0.3% tin petroleum sulphonate. l .O% phenyl-B-naphthylamine i 0.2% tin petroleum sulphonate.

.0% di(3;carbomethoxy-4-hydroAw-phenyl) thioether cresyl 0.2% dlmorpholinyl phenyl methane 1.0% phenyLfl-naphthylamine 0. tin petroleum sulphonate 2. tertiary butyl cresyl phenyl-fl-naphthylaz tin petroleum sulphonate di(3-ca1'bomethoxy-d-hydroxy-phenyl)thioether cresyl .0% zinc di 1-methyl isoamyl) dithiophosphate slotted holders to which lead test pieces were attached by means of screws. For the test-pieces rectangular plates of pure lead 1%" by 1" were mounted vertically just below the surface of the lubricant with the longer axis horizontal. Copper strips, as catalysts, wide and bent into a semicircle 3%" in diameter were placed wholly below the surface of the lubricant and attached by means of vertical copper wires to corks fitted in the beaker covers. Each beaker was also fitted with a thermometer.

C. ENGINE TESTS Tests were carried out in a standard H-2type Lauson engine under the following conditions:

Jacket temperature 210i2 F. Oil sump temperature 28012 F. Test duration hours.

The following test results illustrate the efiectiveness of certain of the compositions contem plated in the present invention as lubricants for 1.1 internal combustion engines operating under severe conditions:

Table 6 Piston Used oil analysis lacquer Beam} g Test Lubricant g fg weight Add No. 1 1055, Percent (mgs y mgs. visc. ual inc KOH rating) per gm.)

87.5% acidless castor oil. 12.5% mineral oil B 7 513 285 2 No. 1+1% phcnyl-fl-naphthylamine). 0.2% tin petroleum sulphonate).

2-.-. 2% di(3-carb0inethoxy-41 8.2 '68 156 a 5.

hydroxyphcnyl)thio- (Mean figures2 tests) other cresyl phosphite.

0.2% dimorpholinyl 7pl iyentyrl 1amethme. u 8.5 sscasoro {12.5% mineral 011 B 509 442 9 4 No. 3+the same additives 8. 3 103' 175 6. 5

employed in test No. 2. (lvileau figulres2 tests) In tests 1 and 3 there was a very heavy buildup of soft black gum on the neck of the inlet valve. In tests 2 and 4 theamount of deposit on the inlet valve was extremely light.

Oil B was a mineral lubricating oil of viscosity.

44" Redwood at 140 F.

The method of. rating piston cleanliness was. that adopted by the Co-ordinating Research Council (C. R. C.) in which a perfectly clean piston is given a rating of 10 and a perfectly black piston a rating of zero.

We claim:

1. A lubricating composition comprising a major proportion of castor oil in which is incorporated a proportion of from 0.05% to 2.0% of a metallic organic compound soluble in castor oil and selected from the group consisting of tin and antimony salts of aliphatic monocarboxylic acids having 12 to 18 carbon atoms, organic sulphonic acids, naphthenic acids, and phenol thioethers and a proportion of from 0.1% to 5.0% of an aromatic secondary amine containing at least three cyclic nuclei, at least two of which nuclei are aromatic nuclei attached directly to the nitrogen atom.

2. A lubricating composition as claimed in claim 1 in which the amine is selected from the group consisting of a compound represented by the general formula where R1, R3 and R4 are aromatic radicals and R2 is a condensed aromatic nucleus having at least ten carbon atoms.

3. A lubricating composition as claimed in claim 1 in which is incorporated a proportion of from 0.2% to 5.0% of a neutral organic phosphite ester of a hydroxy-substituted aromatic thicether.

4. A lubricating composition as claimed in claim 1 in which is incorporated a proportion of from 0.2% to 5.0% of a neutral organic phosphite ester of a hydroxy-substituted aromatic disulfide.

5. A lubricating composition as claimed in claim 1 comprising also a minor proportion of-a further lubricant additive selected from the group consisting of the reaction product of an aldehyde. with a. basic water-soluble amine and the reaction product of a ketone with a basic watersoluble amine.

6. A lubricating composition as. claimed in claim 1, comprising also a proportion of up to -/2% of a mineral oil.

'7. A lubricating composition comprising a major proportion of castor oil in which isv incorporated a proportion of from 0.05% to 2.0 of a castor oil soluble tin salt of an organic. sulphonic acid and a proportion of from 0.1% to 5.0% of an aromatic secondary amine containing at least three cyclic nuclei, at least two of which nuclei,

are aromatic nuclei attached directly to the nitrogen atom.

8. A lubricating composition comprising a major proportion of castor oil in which is incorporated a proportion of from 0.05% to 2.0% of a castor oil soluble antimony salt of anorganic sulphonic acid and a proportion of from 0.1% to 5.0 of an aromatic secondary amine containing at least three cyclic nuclei, at least two of which nuclei are aromatic nuclei attached directly to the nitrogen atom.

9. A lubricating composition comprising a major proportion of castor oil in which is incorporated a proportion of from 0.05% to 2.0% o1- tin petroleum sulphonate and a proportion of from 0.1% to 5.0% of an aromatic secondary amine containing at least three cyclic nuclei, at least two of which nuclei are aromatic nuclei at-' tached directly to the nitrogen atom.

10. A lubricating composition comprising a major proportion of castor oil in which is incor porated a proportion of from 0.05% to 2.0% of antimony petroleum sulphonate and a proportion of from 0.1% to 5.0% of an aromatic sec ondary amine containing at least three cyclic nuclei, at least two of which nuclei are aromatic nuclei attached directly to the nitrogen atom.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,163,856 Rice Dec. 14:, 1915 1,594,983 Sommervill Aug. 3, 1926 2,410,652 Grifiin et al Nov. 5, 1946 2,440,530 Yates Apr. 27, 1948 2,472,503 Minne June 7, 1949 2,551,124- Helmore May 1, 1951 2,579,038 Evans et a1. Dec. 18, 1951 FOREIGN PATENTS Number Country Date 616,881 Great Britain Jan. 28, 194.9 

1. A LUBRICATING COMPOSITION COMPRISING A MAJOR PROPORTION OF CASTOR OIL IN WHICH IS INCORPORATED A PROPORTION OF FROM 0.05% TO 2.0% OF A METALLIC ORGANIC COMPOUND SOLUBLE IN CASTOR OIL AND SELECTED FROM THE GROUP CONSISTING OF TIN AND ANTIMONY SALTS OF ALIPHATIC MONOCARBOXYLIC ACIDS HAVING 12 TO 18 CARBON ATOMS, ORGANIC SULPHONIC ACIDS, NAPHTHENIC ACIDS, AND PHENOL THIOETHERS AND A PROPORTION OF FROM 0.1% TO 5.0% OF AN AROMATIC SECONDARY AMINE CONTAINING AT LEAST THREE CYCLIC NUCLEI, AT LEAST TWO OF WHICH NUCLEI ARE AROMATIC NUCLEI ATTACHED DIRECTLY TO THE NITROGEN ATOM. 